Helminth eggs in marine and river sediments

Abstract

This investigation examines the sources of parasite contamination and their effect on the contamination of three types of marine sediments of a specific coastal region: marine sediments, river sediments, and sewage sludge. In the sludge, concentrations varied between 2 × 10 1 to 3.4 × 10 2 eggs kg −1 with 30% of samples containing at least four different types of eggs (nematode and cestode eggs). In the river sediment, helminths eggs were found in 90% of samples (sector Besos) and in 80% of samples (sector Llobregat). Only 20% of the littoral marine sediments from the Besos were positive for helminth eggs but in the sludge effluent zone all the samples were positive. At 7000 m offshore no samples contained helminth eggs. In the Llobregat sector, 35% of samples contained helminth eggs; there was no apparent difference in the degree of parasite contamination between the littoral (200 m offshore) and the intermediate zones (1000 m offshore). At 4000 and 12 000 m offshore no samples contained helminth eggs. The viability of Ascaris eggs was studied. Globally the percentage of viable eggs was always higher in Besos sector than in Llobregat. If all sediment river samples contained viable eggs we have recognized in some sediment marine sample viable Ascaris eggs: in Besos sector 14% of viable Ascaris eggs were still found at 3000 m and 4000 m offshore while only samples collected from littoral zone in Llobregat sector contained 5% of viable Ascaris eggs.